Large thick-walled plastic containers of the order of two and one-half, five and six gallon sizes, and even larger, are commonly employed for packaging and transporting various liquid and solid material, such as foods, detergents, chemicals and the like, which may be corrosive and/or poisonous.
These containers are usually open head containers having molded plastic container lids including a skirt portion having inwardly extending ribs engaging an outwardly extending lip on the top edge of the container. A sealing ring is also carried by the lid and engages the top edge of the container when the lid is in place on the container. To open these containers, it is necessary to pry the skirt portion of the lid away from the ribs on the container, and to close the container it is necessary to push or force the lid onto the container so that the ribs on the lid will once again snappingly engage the lip on the container. Often times, once the lid is removed from the container, it is not replaced on the container in a sealing manner but merely placed on the top edge of the container, thereby rendering the contents of the container easily accessible to unauthorized persons, more particularly, children.
After considerable research and experimentation, applicant has extended his expertise in child-proof bottle caps to open head containers having molded plastic container lids, wherein a threaded connection is provided between the container and the lid or closure and the lid is provided with a pair of diametrically disposed resiliently biased locking members, pivotally connected to the closure, which cooperate with locking teeth on the container. The ratcheting action of the locking members and teeth allow the closure to be threaded or screwed onto the container and prevent rotation of the closure in the opposite direction to remove the closure. To remove the closure, the user grasps both resiliently biased locking members and pivots them in a direction to release the locking members from the teeth while turning the closure in a direction to remove it from the container.